1. Technical Field
The present principles relate to fuel for combustion engines. More particularly, it relates to a fuel additive for increasing efficiency of diesel fuel combustion engines.
2. Description of Related Art
Ongoing efforts have been made over the years to control the emissions created by the use of hydrocarbon fuels and to increase the performance of such fuels. One method that has been used is to increase the oxygen content of the fuels, for example by adding ethanol, as is done in the Midwest region of the United States, or by adding methyl tertiary butyl ether (MTBE), as is required in California and in major U.S. cities. However, MTBE is quite water soluble and the ground water in many parts of the United States is contaminated by MTBE. However, MTBE itself is a pollutant since it is very water-soluble and any fuel leak will pollute ground water with MTBE. Other proposed methods of increasing the oxygen content of fuels include adding ethers alone or adding ethers mixed with alcohols. Alcohols have the disadvantage that fuels that contain alcohols can become acidic from air oxidation of the alcohol and can form solids that will plug filters and injectors if the fuel is stored for a long period of time. Further, alcohol compounds impart no lubricity to the fuel and can make the fuel more corrosive.
Peroxides have also been proposed as a source of oxygen for fuels, but peroxides are unstable and can cause the chemical breakdown of fuel in storage tanks, which makes the fuel unusable.
At the present time, there is a need for a product that has both a capability of effectively controlling harmful emissions in fuels such as middle distillate fuels and gasoline and a chemical compatibility with such fuels, so that the fuels remain stable for long periods of time under typical storage conditions.
The combustion performance in a combustion chamber of automobile and an oil burning boiler is one of important performance indexes, and it determines whether a fuel oil has properties of energy-saving, environment protection, and the like. For a gasoline product, an important performance index is the antiknock property, and its antiknock index is generally expressed as the average value of an octane number determined by research method (RON) and an octane number determined by motor method (MON). In order to produce a high-octane number gasoline, one method is the improvement of petroleum refining technology by means of catalytic cracking, alkylation, platinum reforming, or the like, but the technological improvement is limited by a variety of factors, including reform and renovation of equipments, funds, a complete set of techniques, and so on; and another method is the addition of a suitable antiknock agent into gasoline.
The energy saving and the reduction of pollution of automobile tail gas exhausted to the environment have become worldwide problems, and they can be realized by three operations: improvement of the refining technology of petroleum, improvement of engine or combustion equipments (e.g., oil burning boiler) and addition of a suitable additive. Components of energy-saving and decontaminating additives for diesel oil, kerosene, heavy oil and resid are roughly divided into two kinds: one kind is peroxides and another kind is oil-soluble substances containing heavy metals. It has been found in uses that the former is unfavorable to the storage of oils, and the latter results in abrasion of engine and causes new environmental pollution.
Antifriction and anticorrosion effects on engine at work given by adding a mixture (not a synthetic) of a tricarboxylic amide or tetracarboxylic amide and an alkali metal or alkali-earth metal salt into a fuel oil have been disclosed in U.S. Pat. No. 4,871,375. However, the content of nitrides in the exhaust gas of automobile is increased by the use of amine compounds because of the addition of nitrogen atom. Moreover, effects of this additive on increasing the antiknock property of gasoline, saving energy of oils such as gasoline, diesel oil, kerosene, resid, and the like and reducing the contamination of exhaust gas have not been described in the literature.
A diesel oil additive has been disclosed in U.S. Pat. No. 5,593,464, and it is a synthetic product of a distilled resid and an alkali metal, alkali-earth metal or rare-earth metal and can inhibit carbon deposit and smoke dust, but whether the additive has an energy-saving effect and an antifriction effect on engine and also whether the additive is applicable to fuel oils other then diesel oil have not been described.
Problems common to these antiknock agents are low effectiveness, large amount, and diseconomy and inconvenience. The other kind of gasoline antiknock agent is oranometallic compounds, and they have high effectiveness and small amount. Tetraethyl lead used for many years has been prohibited because of the toxicity of lead. Ferrocene (dicyclopentadienyl iron) and cyclopentadienylmanganese tricarbonyl (wrong word “tricarboxyl” in the original specification, translator) have been proposed as antiknock agent in U.S. Pat. No. 4,139,349; methylcyclopentadienylmanganese tricarbonyl (wrong word “tricarboxyl” in the original specification, translator) have been proposed as antiknock agent in U.S. Pat. No. 4,437,436 and is produced in Ethyl Co., USA now; and complexes of cerium and .A-inverted., -diones have been proposed as antiknock agent in U.S. Pat. No. 4,211,535. Among these compounds, ferrocene has been prohibited because of a harmful effect on engine, the manganese-base antiknock agents have been limited and prohibited because of its poisonous effect on human nerves and environment, and complexes of cerium and .A-inverted., -diones have a too high cost to popularize.
The combustion of fuel in an internal combustion engine typically results in the formation and accumulation of deposits on various parts of the combustion chamber and on the fuel intake and exhaust systems of the engine. The presence of these deposits in the combustion chamber often result inn the following problems: (1) reduction in the operating efficiency of the engine; (2) inhibition in the heat transfer between the combustion chamber and the engine cooling system; and (3) reduction in the volume of the combustion zone which can cause a higher than design compression ratio in the engine. A knocking engine can also result from deposits forming and accumulating in the combustion chamber.
A prolonged period of a knocking engine can result in stress fatigue and wear in engine components such as, for example, pistons, connecting rods bearings and cam rods. The rate of wear tends to increase under harsh temperature and pressure conditions which exist inside the engine. In addition to limiting the useful life of the components in the engine being used, wear of the components can be costly because the engine components themselves are expensive to produce. Other significant problems associated with wear include, for example, down time for equipment, reduced safety and diminished reliability.
One approach to achieving enhanced fuel economy and thereby reducing the wear of engine components is by improving the efficiency of the internal combustion engine in which the fuel is used. Improvement in the engine's efficiency can be achieved through a number of methods, e.g., (1) improving control over fuel/air ratio; (2) decreasing the crankcase oil viscosity; and, (3) reducing the internal friction of the engine in certain specific areas due to wear. In method (3), for example, inside an engine, about 18 percent of the fuel's heat value, i.e., the amount of heat released in the combustion of the fuel and therefore able to perform work, is dissipated due to internal friction at engine components, e.g., bearings, valve train, pistons, rings, water and oil pumps, etc. Only about 25 percent of the fuel's heat value is converted to useful work at the crankshaft. Friction occurring at the piston rings and parts of the valve train account for over 50 percent of the heat value loss. A lubricity improving fuel additive capable of reducing friction at these engine components by a third preserves an additional three percent of the fuel's heat value for useful work at the crankshaft. Therefore, there has been a continual search for fuel additives which improve the delivery of friction modifier to strategic areas of the engine thereby improving the fuel economy of engines.
For example, U.S. Pat. Nos. 2,252,889, 4,185,594, 4,208,190, 4,204,481 and 4,428,182 disclose anti-wear additives for fuels adapted for use in diesel engines consisting of fatty acid esters, unsaturated dimerized fatty acids, primary aliphatic amines, fatty acid amides of diethanolamine and long-chain aliphatic monocarboxylic acids.
U.S. Pat. No. 4,427,562 discloses a friction reducing additive for lubricants and fuels formed by the reaction of primary alkoxyalkylamines with carboxylic acids or alternatively by the ammonolysis of the appropriate formate ester.
U.S. Pat. No. 4,729,769 discloses a detergent additive for gasoline, which contains the reaction product of a C.sub.6 -C.sub.20 fatty acid ester such as coconut oil and a mono- or di-hydroxy hydrocarbyl amine such as diethanolamine or dimethylaminopropylamine.